High carbon printing inks



2,891,872 Ice Patented June 23, 1959 2,891,872 rncn CARBON PRINTING INKSAndries Voet, Borger, Tex., assignor to J. M. Huber Corporation, Borger,Tex., a corporation of New Jersey No Drawing. Application November 8,1955 Serial No. 545,774

16 Claims. (Cl. 106-28) This invention relates to printing inks and moreparticularly to inks composed principally of carbon black dispersed in apredominantly hydrocarbon vehicle and adapted for use on high speedperfecting presses.

Increased printing speeds have imposed stringent demands on news inks.News inks fashioned in a manner similar to lithographic inks andcontaining 12 to 18 parts of carbon in a vehicle composed of alithographic varnish or a varnish composed of large quantities of rosin,stearin pitch, gilsonite or other resins dissolved in a mineral oil haveproved unsuitable for tank storage and modern distribution systemsbecause of their extreme thixotropic nature. Most of such inks will notoperate on a high speed web press because the body of the ink lackssufiicient fiuidness, causing the paper to pick or tear. One approach toovercoming this difficulty has been a reduction in the carbon content ofnews inks until they now generally consist of to 14% of carbon ground ina mineral oil containing a few percent of a conditioner such as aphaltor gilsonite. The carbon content of such inks is so low as to beunsatisfactory for many purposes so far as concerns blackness of print.

Deficiencies of present news inks are due to the inability to formulateinks which remain fluid and at the same time have body characteristicswhich permit satisfactory operation on a web press performing at highspeed as to effect suflicient carbon concentration when printed toresult in a desirably black imprintation without objectionableshow-through. Attempts to use large amounts of carbon in a mineral oilvehicle containing only small amounts of resins or asphalts produce abody which backs away in the fountain. Large amounts of resins producetemporary good flow but flocculation of the carbon on short periods ofrest will convert the inkinto a gel. Such inks cannot be readily handledin bulk; The substitution of bodied linseed oil usually produces someimprovement in the body but such inks are still overly thixotropic andin addition have suflicient tack to pick or tear the paper at onlymoderately high speed printing.

Accordingly, it is a principal object of this invention to provide inksof high carbon content having improved flow properties, and moreparticularly to provide this type of ink having a predominantlyhydrocarbon vehicle and adapted for use in high speed perfecting or webpresses.

Another object is to produce news inks which give blacker printing andless show-through on a printed sheet.

Another object is to produce news inks which are essentially non-mistingunder high speed printing conditions.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The present invention is a continuation-in-part of my copendingapplication Serial No. 427,340, filed May 3,

The objects of the invention are accomplished by providing a printingink with a vehicle composed of a dispersing agent and an antiflocculentin the presence of an essentially mineral oil hydrocarbon, thehydrocarbon constituting at least about by weight of the vehicle, carbondispersed in the vehicle to at least 16% by weight of the ink, the ratioof yield value, in dynes per sq. cm., to plastic viscosity, in poises,of the dispersion, being less than about 70 at 30 C. l i

The printing process consists essentially in filtering a layer of carbonout of an ink filin and onto the surface of the sheet of paper.Blackness of print will depend on the amount of carbon which is filteredfrom the ink film. The amount of carbon filtered onto the paper dependson the amount of ink film deposited per unit surface and upon theconcentration of carbon in the ink film. Conversely, when using inkshaving hydrocarbon vehicles, these factors determine the amount of oilpenetration and show-through of the printed matter. required for removalof enough oil so that the printed matter is sufliciently rigid toprevent offset and smudging. Finally, since the ink filaments which areresponquire a force greater than a yield value to initiate the flow anda greater force to maintain the flow. The flow characteristics arereadily determinable by known methods which involve essentiallymeasuring the resistance to flow at increasing rates of shear. The rateof shear in reciprocal seconds is then plotted as ordinate against theresistance to flow in dynes per sq. cm. as abscissa. As the rate ofshear is increased the plot tends to assume the form of a straight line.Extrapolation of the straight portion of this curve back to the abscissagives the yield value in dynes per sq. cm. The cotangent of this linewith the abscissa gives the plastic viscosity in poise.

Both yield value and plastic viscosity are important in determining theworking properties of the ink, neither a high viscosity nor a high yieldvalue being desirable. However, the relation between these two valueshas been found a desirable criterion for evaluating the properties ofthe ink. I have now found that inks in which the yield value in dynesper sq. cm. divided by the plastic viscosity in poises is less thanabout 70 will distribute and print satisfactorily on high speedperfecting presses.

Satisfactory blackness on newsprint may be obtained by applying about2.7 grams of carbon per square meter of covered surface. When a news inkcontaining 10% of carbon is employed the application of 2.7 grams ofcarbon will add 24.3 grams of oil and the transparency of the paper willbe greatly increased. Experiments have shown that it is necessary toreduce the oil to about 15 grams per square meter before thetransparency of ordinary newsprint is largely eliminated and the bestresults are obtained when not more than 11 grams are added. Thefollowing table shows the amount of oil transferred from inks of variouscarbon contents when 2.7 grams of carbon are printed:

Grams of oil They also control, to a great extent, the time The use ofinks of high carbon content permits printing with much thinner inkfilms. Thinner films will in turn virtually eliminate misting even inhigh speed web type presses. The amount of misting from inks of variouscarbon contents has been measured by applying a quantity of ink,containing a known percentage of carbon, to the rolls of a mist testingmachine and collecting the mist devolved from the separating side of twocontacting ink rollers. The mist is caught on weighed pieces of aluminumfoil of a given area and the increase in Weight determined. Thefollowing table shows the advantages of the use of inks containing morethan about 16% of carbon:

Percent carbon in ink: Milligrams of mist The use of moderate amounts ofdispersing agents in addition to dispersing the carbon will add certainquality of flow to low carbon content inks but not to high carboncontent inks which nonetheless will flocculate on cessation ofagitation. However, it has now been found that non-flocculating highcarbon content inks can be produced by the addition of antiflocculentsin the presence of dispersing agents. This addition serves to retain thedispersed condition of the carbon, which is obtained when agitation isdiscontinued, thus overcoming the objectionable thixotropic character ofthe ink. It should be pointed out that dispersing agents do not functionas antiflocculents to more than a minor and insignificant extent andantifiocculents do not act as dispersing agents, both agents beingnecessary to prepare and maintain a satisfactory high carbon ink.

Dispersing agents which improve the flow characteristics to low carboncontent inks consist of such materials as gilsonite, asphalts, fluid orsemi-solid tars obtained as residues from petroleum refining, rosin orlimed rosin and the like. Bodied drying oils and modified drying oilshave like qualities if used in considerable amounts. Dispersing agentshaving these characteristics can be recognized by the addition of 2% toto a grind of 12 parts channel black in 88 parts of white mineral oil.Before the addition the ink tends to drop in chunks from a spatula whileafter the addition it will flow in a long string.

Certain partially refined mineral oils can be obtained containingpartially oxidized and polymerized tars which act as dispersing agents.The oils themselves are dark in color and on vacuum distillation give ablack waxy deposit which effectively disperses carbon black. Thedispersing agent required to produce the inks of this in vention can besupplied partially or entirely by the use of such tarry petroleumresidues.

Among the materials we have found to be useful as antifiocculents arevarious salts of mahogany acids and particularly the alkaline earthsalts such as the barium and calcium, as well as the dibutylamine saltsof mahogany acids. Also, high molecular weight oil soluble substancessuch as dehydro abietyl amine and sorbitol sesquioleate performsatisfactorily as antiflocculents. The effect of such substances can beshown in the following manner: An ink composed of 12 parts of channelcarbon, 3 parts of dispersing agent such as gilsonite and 83 parts of amineral oil is first prepared. This ink is divided into two portions. Tothe first portion 4% of its weight of mineral oil is added and to thesecond portion 4% of its weight of antiflocculent. Portions of each inkare placed in test tubes and held at about 50 C. for four to eight hoursand the tubes are then examined in a dark room with ultraviolet light.The sample containing no antifiocculent will fluoresce a pale blue dueto syneresis and separation of oil. The fluorescence may be particularlystrong over extended patches due to the free oil which collects on theglass. The treated sample will show only a minor amount or be completelyfree of fluorescence.

Satisfactory ink compositions are illustrated by the following examples:

Example 1 An ink was prepared by dispersing 25 parts of channel carbonblack in a mixture of 68 parts of a medium viscosity mineral oil and 7parts of a liquid tar from pctroleum refining which acted as adispersing agent. This ink was of a heavy buttery nature. To thisbuttery material 4 parts of a 50% solution of the neutral barium salt ofmahogany acid in mineral oil was added. The resulting ink flowed readilyand printed in a satisfactory manner on a newspaper press operating at aspeed of 1200 feet per minute. The ink has a viscosity at 30 C. of 19.2poises and yield value of 10 dynes per sq. cm. The ratio of yield pointto viscosity was 0.5. The ink retained its flow properties after twomonths storage.

This ink was compared on a high speed newspaper press with a controlsample of normal ink containing 11% of carbon. In the first case theexperimental ink was printed with the same film thickness of ink as thecontrol sample. No flooding of plates resulted and the print wasextremely black and there was much less showthrough than with thecontrol. The fountain was then adjusted to reduce the ink film ofexperimental ink so that a normal amount of carbon was applied to thepaper. No misting was observed with the experimental ink andshow-through was reduced to that due to the normal transparency of thepaper.

Example 2 An ink was prepared containing 20 parts of a fine particlesize furnace carbon, 3 parts of gilsonite and 77 parts of a mediumviscosity mineral oil. This ink was of a short consistency. The additionof 5% of mineral oil to a portion of this ink did not produce an inkwith satisfactory flow. The addition of 5% of a 50% solution of thebarium salt of mahogany acid in mineral oil produced an ink with goodflow and of good printing quality. The viscosity of this ink at 30 C.was 18.9 poises and the yield value was 990 dynes per sq. cm. The ratioof yield value to viscosity was 52. This ink flowed readily withoutagitation after three months storage.

Example 3 Example 4 An ink prepared from 73 parts of mineral oil, 6parts Number 3 linseed oil to act as dispersing agent, 17 parts ofchannel carbon and 4 parts of antiflocculent dehydroabietyl amine hadgood flow properties. The viscosity was 8 poises and the yield value was330 dynes per sq. cm. This ink printed satisfactorily on newsprint at aspeed of 1200 feet per minute.

Example 5 Inks were made of the following compositions in which thedeflocculent was a soft petroleum residue tar and the antifiocculent wasa 50% solution in mineral oil of a mixed barium and zinc salt ofmahogany acid. The mineral oil had a viscosity of 2 poises.

Ink Number 1 2 3 4 6 6 Mineral Oil 59 66 73 76 78. 3 76 Carbon Black 3025 20 17 17 20 Dispersing Agent" 6 5 4 4 4 4 antiflocculent 5 4 3 3 0. 7Viscosity-poise 31. 7 12. 7 7. 06 4. 1 10. 9 Yield Value, dynes per sq.

cm 1, 950 0. 0 0. 0 0. 0 46. 2 1, 040 Ratio Yield Value to Viscoslty 620. 0 0. 0 0. 0 9. 2 95 Each of these inks printed satisfactorily exceptNumber 6 which contained no antiflocculent and 'would not feedsatisfactorily from the fountain. Each of the first four was free ofmisting and remained in a fiowable condition after one monthstorage.

Example 6 An ink satisfactory for use in heat set printing was preparedas follows: A mixture of 3 parts of gilsonite and 7 parts of rosin bothof which act as dispersing agents was dissolved in 63 parts of mineralseal oil and 2 parts of toluene. This was heated to 70 C. and 23 partsof unpressed channel carbon black was stirred in. After cooling to 30C., 5 parts of a 50% solution in mineral oil of a mixed barium and zincsalt of mahogany acid was stirred in and the mixture given one pass overa 3 roller ink mill. The ink had a viscosity of 22.8 poises and a yieldpoint of 127 dynes per sq. cm. This ink printed satisfactorily at 1200feet per minute on both newsprint and coated paper. After standing twoweeks the ink had acquired a slight body but would flow readily withoutstirring if the container was given only a slight jar.

The inks of this invention are based generally on a hydrocarbon vehicleand particularly on a mineral oil basis. The nature of the mineral oilis not particularly significant since highly refined white mineral oil,highly unsaturated oils, cyclic hydrocarbons and oils showing aconsiderable aromatic content have been used successfully. However, wehave found that large amounts of dissolved resinous materials such asgilsonite and rosin contribute to the body and tack and are undesirable.In general the hydrocarbon oil will constitute in excess of 80% of thevehicle used to disperse the carbon and in our preferred inks in excessof 90%. The dispersing agents are often dark colored and if used in toolarge an amount will bleed into the paper and produce staining. Themaximum amount of the antiflocculent will be governed by cost. However,more than 5% in the ink will produce little added eifect, but will do noharm.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A process for producing a printing ink having a carbon black contentof at least 16% by weight of the ink and a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., which comprises admixing said carbon black with asubstantially hydrocarbon vehicle comprising at least 80% by weight ofmineral oil, a dispersing agent selected from the group consisting ofgilsonite, asphalt, asphaltic petroleum residues, rosin, limed rosin andbodied drying oil and an antiflocculent, said antiflocculent having theproperty of substantially preventing oil syneresis after four hoursstorage at 50 C. of an ink composed of 12 parts channel carbon black, 3parts gilsonite and 83 parts mineral oil to which the antiflocculent isadded in an amount equivalent to 4% by weight based on the ink.

2. A process for producing a printing ink having a ratio of yield value,in dynes per sq. cm., to plastic viscosity, in poises, of less thanabout 70 at 30 C., which comprises admixing carbon black in an amount ofabout 16% to 30% by weight of said ink with substantially hydrocarbonvehicle containing at least 80% 6 by weight of mineral oil, a dispersingagent selected from the group consisting of gilsonite, asphalts,asphaltic petroleum residues, rosin, limed rosin and bodied drying oiland an antiflocculent, said antiflocculent having the property ofsubstantially preventing oil syneresis after four hours storage at 50 C.of an ink composed of 12 parts channel carbon black, 3 parts gilsoniteand 83 parts mineral oil to which the antiflocculent is added ifik anamount equivalent to 4% by weight based on the 1 3. A process forproducing a high speed printing having a carbon black content of atleast 16 by weight of the ink, which comprises admixing an essentiallymineral oil vehicle with said carbon black, a dispersing agent selectedfrom the group consisting of gilsonite, as-

phalts, asphaltic petroleum residues, rosin, limed rosin and bodieddrying oil and an antiflocculent, said antiflocculent comprising analkaline earth metal salt of mahogany acid.

4. The process according to claim 3 wherein the alkaline earth metalsalt of mahogany acid is a barium salt.

5. The process according to claim 3 wherein the alkaline earth metalsalt of mahogany acid is a calcium salt.

6. A process for producing a printing ink having a carbon black contentof at least 16% by weight of the ink and a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., which comprises admixing said carbon black with asubstantially hydrocarbon vehicle comprising at least by weight mineraloil, a dispersing agent consisting of asphaltic petroleum residue and abarium salt of mahogany acid as antiflocculent.

7. A process for producing a printing ink having a carbon black contentof at least 16% by weight of the ink and a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., which comprises admixing said carbon black with asubstantially hydrocarbon vehicle comprising at least 80% by weightmineral oil, a dispersing agent selected from the group consisting ofgilsonite, asphalts, asphaltic petroleum residues, rosin, limed rosinand bodied drying oil and a dibutylamine salt of mahogany acid as anantiflocculent.

8. A process for producing a printing ink having a carbon black contentof at least 16% by weight of the ink and a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., which comprises admixing said carbon black with asubstantially hydrocarbon vehicle comprising at least 80% by Weightmineral oil, a dispersing agent selected from the group consisting ofgilsonite, asphalts, asphaltic petroleum residues, rosin, limed rosinand bodied drying oil, and dehydro abietyl amine as an antiflocculent.

9. A process for producing a printing ink having a. carbon black contentof at least 16% by weight of the ink and a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., which comprises admixing said carbon black with asubstantially hydrocarbon vehicle comprising at least 80% by weightmineral oil, a dispersing agent selected from the group consisting ofgilsonite, asphalts, asphaltic petroleum residues, rosin, limed rosinand bodied drying oil and sorbitol sesquioleate as an antiflocculent.

10. A high speed black printing ink having a ratio of yield value, indynes per sq. cm., to plastic viscosity, in poises, of less than about70 at 30 C., comprising a substantially hydrocarbon vehicle comprisingat least 80% by weight of mineral oil, carbon black, a dispersing agentand an antiflocculent, said carbon black constituting between about 16%and 30% by weight of the ink, said dispersing agent being selected fromthe group consisting of gilsonite, asphalts, asphaltic petroleumresidues, rosin, limed rosin and bodied drying oil, and said anti- "27flocoulent having the property of substantially preventing oil syneresisafter four hours storage at 50 C. of an ink composed of 12 parts channelcarbon black, 3 parts gilsonite and 83 parts mineral oil to which theantifiocculent is added in an amount equivalent to 4% by weight based onthe ink.

11. A black printing ink having a ratio of yield value, in dynes per sq.cm., to plastic viscosity, in poises, of less than about 70 at 30 C.comprising in admixture with carbon black a substantially hydrocarbonvehicle comprising at least 80% by weight of mineral oil, a dispersingagent selected from the group consisting of gilsonite, asphalts,asphaltic petroleum residues, rosin, limed rosin and bodied drying oiland an alkaline earth metal salt of mahogany acid as an antifiocculent,said carbon black being at least 16% by weight of the ink.

12. The product of claim 11 wherein the alkaline earth metal salt ofmahogany acid is a barium salt.

13. The product according to claim ll wherein the alkaline earth metalsalt of mahogany acid is a calcium salt.

14. A black printing ink having a ratio of yield value, in dynes per sq.cm., to plastic viscosity, in poises, of less than about 70 at 30 C.comprising in admixture with carbon black a substantially hydrocarbonvehicle comprising at least 80% by Weight of mineral oil, a dispersingagent selected from the group consisting of gilsonite, asphalts,asphaltic petroleum residues, rosin, limed rosin and bodied drying oiland a dibutylamine salt of mahogany acid as an antifiocculent.

15. A black printing ink having a ratio of yield value,

in dynes per sq. cm., to plastic viscosity, in poises, of less thanabout at 30 C. comprising in admixture with carbon black a substantiallyhydrocarbon vehicle comprising at least by weight of mineral oil, adispersing agent selected from the group consisting of gilsonite,asphalts, asphaltic petroleum residues, rosin, limed rosin and bodieddrying oil and dehydro abietyl amine as an antiflocculent.

16. A black printing ink having a ratio of yield value, in dynes per sq.cm., to plastic viscosity, in poises, of less than about 70 at 30 C.comprising in admixture with carbon black a substantially hydrocarbonvehicle comprising at least 80% by weight of mineral oil, a dispersingagent selected from the group consisting of gilsonite, asphalts,asphaltic petroleum residues, rosin, limed rosin and bodied drying oiland sorbitol sesquioleate as an antifiocculent.

References Cited in the file of this patent UNITED STATES PATENTS2,062,159 Brizzolara et al. Nov. 24, 1936 2,220,952 Brill Nov. 12, 19402,453,558 Voet Nov. 9, 1948 2,675,320 Cristopher et al. Apr. 13, 1954FOREIGN PATENTS 360,948 Great Britain Nov. 9, 1931 OTHER REFERENCESEllis: Printing Inks, Reinhold 1940, p. 217. Schwartz-Perry: SurfaceActive Agents, Inter Science Publishers, 1949 pp. 94, 230, 324, 325, and487.

1. A PROCESS FOR PRODUCING A PRINTING INK HAVING A CARBON BLACK CONTENTOF AT LEAST 16% BY WEIGHT OF THE INK AND A RATIO OF YIELD VALUE, INDYNES PER SQ. CM., TO PLASTIC VISCOSITY, IN POISES, OF LESS THAN ABOUT70 AT 30*C., WHICH COMPRISES ADMIXING SAID CARBON BLACK WITH ASUBSTANTIALLY HYDROCARBON VEHICLE COMPRISING AT LEAST 80% BY WEIGHT OFMINERAL OIL, A DISPERSING AGENT SELECTED FROM THE GROUP CONSISTING OFGILSONITE, ASPHALT, ASPHALTIC PETROLEUM RESIDUES, ROSIN, LIMED ROSIN ANDBODIED DRYING OIL AND AN ANTIFLOCCULENT, SAID ANTIFLOCCULENT HAVING THEPROPERTY OF SUBSTANTIALLY PREVENTING OIL SYNERESIS AFTER FOUR HOURSSTORAGE AT 50*C. OF AN INK COMPOSED OF 12 PARTS CHANNEL CARBON BLACK, 3PARTS GILSONITE AND 83 PARTS MINERAL OIL TO WHICH THE ANTIFLOCCULENT ISADDED IN AN AMOUNT EQUIVALENT TO 4% BY WEIGHT BASED ON THE INK.